German rental car passage through Bosnia

I would ask that rental agency again whether they have any exception for this stretch of road, or continue shopping around. If booking through www.autoeurope.com, they ask you to enter the destinations in a list, which must then be confirmed by a live agent before the booking is completed.

See also this discussion from earlier this year: https://community.ricksteves.com/travel-forum/croatia/rental-car-restrictions-croatia-to-mostar-or-through-bosnian-strip-of-coast.

Rick's book says that the passport check at each of those Bosnian borders is often just a wave-through, in which case they're not going to check the car's papers, but insurance coverage might be your bigger concern.

You have to distinguish between what one hire company's policy is, and what is the law. I have heard that some hire companies will not permit you to take their cars into Bosnia. Some only prohibit German brands such as BMW, Mercedes, Audi and VW, presumably because these are seen as higher risk in terms of being stolen.

In terms of the law, any car can enter Bosnia, providing that it has the correct insurance cover. In Europe this is refered to as Green Card cover - a scheme which provides a standard (green) form stating in which country the car is insured. The forms are issued by the insurance company covering the car, but in practice, you get them from the hire company.

If the hire company prohibit Bosnia, or refuses to provide a green card you can take a ferry, and avoid Bosnia at Neum. The ferry runs from Ploce to Trpanj and is operated by Jadrolinija. Check out Google maps and the Jadrolinija site for more details.